Two-photon or higher-order absorbing optical materials for generation of reactive species

ABSTRACT

Disclosed are highly efficient multiphoton absorbing compounds and methods of their use. The compounds generally include a bridge of pi-conjugated bonds connecting electron donating groups or electron accepting groups. The bridge may be substituted with a variety of substituents as well. Solubility, lipophilicity, absorption maxima and other characteristics of the compounds may be tailored by changing the electron donating groups or electron accepting groups, the substituents attached to or the length of the pi-conjugated bridge. Numerous photophysical and photochemical methods are enabled by converting these compounds to electronically excited states upon simultaneous absorption of at least two photons of radiation. The compounds have large two-photon or higher-order absorptivities such that upon absorption, one or more Lewis acidic species, Lewis basic species, radical species or ionic species are formed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit as a continuation of U.S. applicationSer. No. 10/442,431, filed May 20, 2003 now U.S. Pat. No. 7,235,194,issued Jun. 26, 2007, and as a continuation of U.S. application Ser. No.09/292,652, filed Apr. 15, 1999, now U.S. Pat. No. 6,608,228, and as acontinuation-in-part of U.S. application Ser. No. 08/965,945, filed Nov.7, 1997, now U.S. Pat. No. 6,267,913, issued Jul. 31, 2001, and claimsthe benefit of U.S. Provisional Application Ser. No. 60/082,128, filedApr. 16, 1998, all of which are incorporated herein by reference intheir entirety. Additionally, U.S. Pat. No. 6,267,913 claims benefit toProvisional Applications Nos. 60/029,437 and 60/030,141, both filed Nov.12, 1996.

ORIGIN OF INVENTION

The invention described herein was made in the performance of work undera NASA contract and is subject to the provisions of Public Law 96-517(35 U.S.C. 202) in which the Contractor has elected to retain title. Theinvention was also partially supported by the United States Governmentthrough the Office of Naval Research (ONR Grant Nos. N00014-95-1-1319),Air Force Office of Scientific Research (AFSOR Grant No. AFS5F49620-97-1-0200), and the National Science Foundation (NSF Grant No.CHE 94-08701, Amendment 001).

BACKGROUND OF THE INVENTION

The invention described herein relates generally to materials whichexhibit nonlinear absorptive properties as described in U.S. patentapplication Ser. No. 08/965,945, now U.S. Pat. No. 6,267,913, which isincorporated herein by reference. More particularly, the presentinvention relates to structural variants of those materials which havehigh two-photon or higher order absorptivities and which, due toabsorption of multiple photons, undergo chemistry with high efficiency,including, but not limited to, the creation of Lewis acidic species,Lewis basic species, radical species and ionic species.

For years, the possible applications of using two-photon or higher-orderabsorption for a variety of applications including optical limiting,optical memory applications, microfabrication, and rational drugdelivery have been considered. There are two key advantages oftwo-photon or higher-order induced processes relative to single-photoninduced processes. 1) Whereas single-photon absorption scales linearlywith the intensity of the incident radiation, two-photon absorptionscales quadratically with incident intensity and higher-orderabsorptions will scale with yet higher powers of incident intensity. Asa result, it is possible to perform multiphoton processes with threedimensional spatial resolution. 2) Because these processes involve as afirst step the simultaneous absorption of two or more photons, thechromophore is excited with a number of photons whose total energyequals the energy of multi-photon absorption peak but where each photonis of insufficient energy to excite the molecule individually. Becausethe exciting light is not attenuated by single-photon absorption in thiscase, it is possible to excite molecules at a depth within a materialthat would not be possible via single-photon excitation by use of a beamthat is focused to that depth in the material. These two advantages alsoapply to, for example, excitation within tissue or other biologicalmaterials. In multiphoton lithography or stereolithography, thenonlinear scaling of absorption with intensity can lead to the abilityto write features below the diffraction limit of light and the abilityto write features in three dimensions, which is also of interest forholography.

It was discovered in accordance with an earlier invention (as describedin U.S. application Ser. No. 08/965,945, which is incorporated herein byreference) that molecules that have two or more electron donors, such asamino groups or alkoxy groups, connected to aromatic or heteroaromaticgroups as part of a π-electron bridge exhibit unexpectedly and unusuallyhigh two-photon or higher-order absorptivities in comparison to, forexample dyes, such as stilbene, diphenyl polyenes, phenylene vinyleneoligomers and related molecules. In addition, it was found that thestrength and position of the two-photon or higher-order absorption canbe tuned and further enhanced by appropriate substitution of theπ-electron bridge with accepting groups such as cyano. It was alsodiscovered in accordance with the earlier invention that molecules thathave two or more electron acceptors, such as formyl ordicyanomethylidene groups, connected to aromatic or heteroaromaticgroups as part of a π-electron bridge exhibit unexpectedly and unusuallyhigh two-photon or higher-order absorptivities in comparison to, forexample dyes, such as stilbene, diphenyl polyenes, phenylene vinyleneoligomers and related molecules. The strength and position of thetwo-photon or higher-order absorption can likewise be tuned and furtherenhanced by appropriate substitution of the π-electron bridge withdonating groups such as methoxy.

Realization of many of the possible applications of two-photon orhigher-order absorption by dyes rests on the availability ofchromophores with both large two-photon or higher-order absorption crosssections and structural motifs conducive to excited state chemicalreactivity.

In 1931 Göppert-Mayer predicted molecular two-photon absorption,[Göppert-Mayer, M. Ann. Phys. 1931, 9, 273] and upon the invention ofpulsed ruby lasers in 1960, experimental observation of two-photonabsorption became reality. Multiphoton excitation has found applicationin biology and optical data storage, as well as in other applications.[Strickler, J. H.; Webb, W. W., Opt. Lett. 1991, 1780; Denk, W.;Strickler, J. H.; Webb, W. W., Science 1990, 248, 73; Yuste, R.; Denk,W., Nature (London) 1995, 375, 682; Williams, R. M.; Piston, D. W.;Webb, W. W., FASEB J. 1994, 8, 804; Xu, C.; Zipfel, W.; Shear, J. B.;Williams, R. M.; Webb, W. W., Proc. Natl. Acad. Sci. 1996, 93, 10763;Rentzepis, P. M.; Parthenopoulos, D. A., Science, 1989, 245, 843;Dvornikov, A. S.; Rentzepis, P. M., Advances in Chemistry Series 1994,240, 161; Strickler, J. H.; Webb, W. W., Adv. Mat. 1993, 5, 479, U.S.Pat. Nos. 4,228,861, 4,238,840, 4,471,470, 4,333,165, 4,466,0805,034,613 4,041,476, 4,078,229]. Although interest in multiphotonexcitation has exploded, there is a paucity of two-photon absorbing dyeswith adequately strong two-photon absorption in the correct spectralregion for many applications. Further, there is a paucity of suchchromophores that upon multiphoton excitation undergo predictable andefficient chemical reactions.

Chemistry induced by the linear absorption of electromagnetic radiation(single photon) has been proposed and exploited for polymerizationinitiation, photocrosslinking of polymers, holography, computer memorystorage, microfabrication, medicine, and biochemistry among many otherapplications. Chemistry induced by linear absorption, however, allowsspatial control largely limited to two dimensions (i.e., a surface). Theinvention described herein allows spatial control of photoinducedchemistry over three dimensions.

SUMMARY OF THE INVENTION

The present invention provides compositions of matter that have largetwo-photon or higher-order absorptivities and which upon two-photon orhigher-order absorption lead to formation of one or more of Lewis acidicspecies, Lewis basic species, radical species and ionic species.

It was discovered in accordance with the present invention thatchromophores that include the specific structural motifs described belowallow efficient and hitherto unexplored access via multiphotonabsorption to species of great material engineering, biological, andmedicinal importance.

For example, compositions of the present invention are useful whenincorporated into solutions, prepolymers, polymers, Langmuir-Blodgettthin films, self-assembled monolayers, and cells. The compositions canbe advantageously modified to allow for variation of ease of dissolutionin a variety of host media, including liquids and polymeric hosts, bychanging the nature of the substituents attached to the centralπ-conjugated framework of the molecule as well as either the donors oracceptors, or both. In addition, by controlling the length andcomposition of the π-electron bridge of the molecule, it is possible tocontrol the position and strength of the two-photon or higher-orderabsorption and the two-photon or higher-order excited fluorescence.

Examples of compositions in accordance with the present invention havethe general formulas as shown below.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to ensure a complete understanding of the present invention,the following drawings are provided in which:

FIG. 1 is a graph showing the rate of polymerization of monomethyl-etherhydroquinone (MEHQ) inhibited Sartomer SR9008 initiated bybis-dibutylaminostilbene (BDAS) and two-photon absorptivity as afunction of initiation wavelength.

FIGS. 2 a, b, c and d are SEM micrographs of cantilever and opticalwaveguide structures fabricated in solid films consisting of 30% w/wPSAN (75% polystyrene: 25% polyacrylonitrile copolymer), 69.9% w/wreactive monomer (50% inhibitor-free Sartomer SR9008 and 50% SartomerSR368) and 0.1% w/w dye (1,4-bis(bis(dibutylamino)styryl)2,5-dimethoxybenzene.

FIGS. 3 a and 3 b show UV-visible light absorption spectra for TPS-HFA,Na-DMAS and TPS-DMAS.

FIG. 4 shows two-photon fluorescence excitation spectra of Na-DMAS andTPS-DMAS.

FIG. 5 shows the two-photon fluorescence spectra of Na-DMAS and TPS-DMASas a result of “pumping” at 560 nm.

FIG. 6 illustrates the potential chemical structure of photoacidgenerator compounds having strong two-photon absorption according to theinvention.

FIGS. 7 and 8 illustrate the chemical structure of aniline diacrylate(ADA), a composition according to the invention, and its absorptionspectrum, respectively.

FIG. 9 shows fluorescence spectra of aniline and aniline diacrylate(ADA), after two-photon excitation at 300 nm.

FIGS. 10 and 11 show SEM micrograph and EDS spectrum of Ag-coated poly(ADA) column.

DETAILED DESCRIPTION

To ensure a complete understanding of the invention, the followingdefinitions are provided:

Bridge: a molecular fragment that connects two or more chemical groups.

Donor: an atom or group of atoms with a low ionization potential thatcan be bonded to a π (pi)-conjugated bridge.

Acceptor: an atom or group of atoms with a high electron affinity thatcan be bonded to a π (pi)-conjugated bridge.

A more complete description of electron donors or donating groups andelectron acceptors or electron accepting groups can be found in J.March, Advanced Organic Chemistry: Reactions, Mechanisms and Structure,Fourth edition, Wiley-Interscience, New York, 1992, Chapter 9.

Aromatic group: a carbocyclic group that contains 4n+2 π electrons,where n is an integer.

Heteroaromatic group: a cyclic group of atoms, with at least one atomwithin the ring being an element other than carbon, that contains 4n+2 πelectrons where n is an integer.

A more complete description of aromaticity and heteroaromaticity can befound in J. March, Advanced Organic Chemistry: Reactions, Mechanisms andStructure, Fourth edition, Wiley-Interscience, New York, 1992, Chapter2.

Chromophore: a molecule or aggregate of molecules that can absorbelectromagnetic radiation.

Simultaneous: refers to two (or more) events that occur within theperiod of 10⁻¹⁴ sec.

Two-Photon Absorption: process wherein a molecule absorbs two quanta ofelectromagnetic radiation.

Multiphoton Absorption: process wherein a molecule absorbs two or morequanta of electromagnetic radiation.

Excited State: an electronic state of a molecule higher in energy thanthe molecule's ground state, often accessed via absorption ofelectromagnetic radiation and having a lifetime greater than 10⁻¹³ sec.A more complete discussion of excited states can be found in P. W.Atkins, Physical Chemistry, Fifth edition, W.H. Freeman, New York, 1994and N. J Turro, Modern Molecular Photochemistry, Benjamin/CummingPublishing Company, Menlo Park, 1978.

Heterolytic cleavage: fragmentation of a two-electron chemical bond suchthat the two electrons that composed the bond both reside on one of thetwo fragments formed.

Homolytic cleavage: fragmentation of a two-electron chemical bond suchthat each of the two fragments formed has one of the two electrons thatcomposed the bond.

A more complete description of bond cleavage can be found in J. March,Advanced Organic Chemistry: Reactions, Mechanisms and Structure, Fourthedition, Wiley-Interscience, New York, 1992, page 205.

Two-photon or higher-order absorption: phenomenon wherein a moleculesimultaneously absorbs two or more photons (also referred to asmulti-photon absorption) without the actual population of an excitedstate by the absorption of a single photon.

In many cases, as will be made clear below, the molecules we teach havelarge two-photon or higher-order absorptivities and are themselves novelcompositions of matter. The general formulas below are not inclusive ofall the structures which we teach for use as two-photon or higher-orderabsorbers that lead to formation of Lewis acidic species, Lewis basicspecies, radical species, and ionic species. Other compositions whichhave the characteristic electronic properties as well as otheradvantageous properties for a variety of applications will also becomeapparent to those with ordinary skill in the art, when one considers theexamples described in the general structures below.

U.S. application Ser. No. 08/965,945 described, in part, four structuralmotifs for chromophores with high two-photon or multiphotonabsorptivities in which the position of two-photon or multiphotonabsorption bands may be controlled. The current invention focuses on twonew structural motifs that modify these chromophores such that, uponabsorption of multiple photons, the chromophores will undergo chemistrywith high efficiency to create one or more of Lewis acidic species,Lewis basic species, radical species, and ionic species.

Generally, the two new structural motifs of the present invention are:

-   -   (1) iodonium and sulfonium salts for use as multiphoton        absorption initiated sources of Lewis acids; and    -   (2) fluorenyl and dibenzosuberenyl moieties for use as        multiphoton absorption initiated sources of one or more of Lewis        acids, Lewis bases, radical species, and ionic species.

where L_(g) (standing for a leaving group) and D_(c) will be definedbelow.

The modifications used in our previous invention to tune the energeticposition of the two-photon or higher-order absorption state ofchromophores apply to the invention herein as well.

The advantageous inclusion of moieties of known excited state reactivityin chromophores with strong two-photon or multi-photon absorption allowsthe compounds described herein to have a great variety of novel anduseful applications including, but not limited to

-   -   (1) two-photon generation of charge carriers, especially in        photorefractive polymers;    -   (2) initiation of changes in host media to allow the writing of        holographic information;    -   (3) optical lithography and three dimensional optical memory;    -   (4) microfabrication of three dimensional objects; and    -   (5) in vivo or in vitro decaging of biochemical substrates for        biological, physiological, or medicinal purposes.

A more extensive listing of applications that would be renderedsubstantially more useful by virtue of the large two-photon ormulti-photon absorptivities of the compounds described herein can befound for example in U.S. Pat. Nos. 4,228,861, 4,238,840, 4,471,470,4,333,165, 4,466,080 and 5,034,613.

Sulfonium- and Iodonium-Containing Chromophores

Chromophores of the present invention with large two-photon andmulti-photon absorptivities containing the sulfonium or the iodoniummoiety will, upon two-photon or multi-photon excitation, efficientlyform protic acid. Photoacid generation using compounds containingsulfonium or iodonium moieties has been documented in R. S. Davidson,“The Chemistry of Photoinitiators—Some Recent Developments”, J.Photochem. Photobiol. A: Chem., 73, 81-96 (1993) and M. Shirai and M.Tsunooka, “Photoacid and Photobase Generators: Chemistry andApplications to Polymeric Materials”, Prog. Polym. Sci., 21, 145 (1996).None of these disclosed molecules was, however, a strong two-photonabsorber. In contrast, at least some of the compositions of the presentinvention have a structural framework having strong two-photonabsorption and exhibit all of the advantageous characteristics oftwo-photon absorbers.

Synthesis of Sulfonium- and Iodonium-Containing Chromophores

Methods for the synthesis of sulfonium salts are well documented in J.L. Dektar and N. P. Hacker, “Photochemistry of Triarylsulfonium Salts”,J. Am. Chem. Soc., 112, 6004-6015 (1990), and U.S. Pat. No. 5,446,172,by Crivello, et al., and the references cited therein, each of which isincorporated herein by reference.

Methods for the synthesis of iodonium salts are well documented in C.Herzig and S. Scheiding, German Patent 4,142,327, CA 119,250,162 and C.Herzig, European Patent 4,219,376, CA 120,298,975, which areincorporated herein by reference.

Structure of Sulfonium- and Iodonium-Containing Chromophores

In the structural formulae herein, an asterisk (*) identifies the atomof attachment to a functional group and implies that the atom is missingthe equivalent of one hydrogen that would normally be implied by thestructure in the absence of the asterisk, “—” indicates a single bondbetween 2 atoms, “═” indicates a double bond between 2 atoms, and “≡”indicates a triple bond between 2 atoms.

One embodiment of the invention includes compounds with one of the fourfollowing general formulae

In these formulae:

A_(a) and A_(b)

are independently selected from I⁺ or S⁺. To satisfy the proper bondingcoordination, when A_(a) or A_(b) is an I⁺ group, there is only one Rgroup attached to the I⁺ group; that is, R_(a), R_(b), R_(c), or R_(d)may be nothing, as required.

Anionic Counterions

All cationic species may be accompanied by counterions appropriate tomake an electrically neutral complex. If, for example, the cationicspecies carries a double positive charge, it will be accompanied byeither two singly charged anionic species or by one doubly chargedanionic species. Anionic species that may be used include, but are notlimited to, Cl⁻, Br⁻, I⁻, and SbF₆ ⁻.

m, n, and o

are integers and are independently selected such that 0≦m≦10, 0≦n≦10,and 0≦o≦10.

X, Y, and Z

may be the same or different and may be CR_(k)═CR_(l), O, S, or N—R_(m);R_(k), R_(l), and R_(m) are defined below.

R_(a), R_(b), R_(c), and R_(d)

may be the same or different and may be

-   -   (i) H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10 and 1≦β≦25;    -   (iv) an aryl group;    -   (v) a fused aromatic ring;    -   (vi) a polymerizable functionality; and    -   (vii) nothing when A_(a) is I⁺ or A_(b) is I⁺.        R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l) and R_(m)

may be the same or different and may be

-   -   (a) H;    -   (b) a linear or branched alkyl group with up to 25 carbons;    -   (c) —(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1),        —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CN, —(CH₂CH₂O)_(α)—(CH₂)_(β)Cl,        —(CH₂CH₂O)_(α)—(CH₂)_(β)Br, (CH₂CH₂O)_(α)—(CH₂)_(β)I,        —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10 and 1≦β≦25;    -   (d) an aryl group;    -   (e) a fused aromatic ring;    -   (f) a polymerizable functionality; or    -   (g) a group selected from the group consisting of        —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, and        phenyl, where R_(e1), R_(e2), R_(e3), R_(e4) are independently        selected from the group consisting of        -   (1) H;        -   (2) a linear or branched alkyl group with up to 25 carbons;        -   (3) phenyl; and        -   (4) a polymerizable functionality.            Aryl Group

When any of R_(a), R_(b), R_(e), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l) or R_(m) is an aryl group, they may be arylgroups of the formula

where B is —S— or —O—, and R_(A1), R_(A2), R_(A3), R_(A4), R_(A5),R_(A6), R_(A7), and R_(A8) are one of the following:

-   -   (i) H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) phenyl; and    -   (iv) —NR_(A9)R_(A10), and —OR_(A11), where R_(A9), R_(A10), and        R_(A11) are independently selected from H, a linear or branched        alkyl group with up to 25 carbons, and phenyl.        Fused Aromatic Ring

When any of R_(a), R_(b), R_(e), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l) or R_(m) is a fused aromatic ring, they maybe

where * indicates the atom through which the fused aromatic ring isattached.Polymerizable Functionality

When any of R_(a), R_(b), R_(e), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l), R_(m), R_(e1), R_(e2), R_(e3), or R_(e4) isa polymerizable functionality, they may preferably be selected from thefollowing:

-   -   (a) vinyl, allyl, 4-styryl, acroyl, methacroyl, epoxide (such as        cyclohexene oxide), acrylonitrile, which may be polymerized by        either a radical, cationic or anionic polymerization;    -   (b) isocyanate, isothiocyanate, epoxides such that the        polymerizable functionality may be copolymerized with        difunctional amines or alcohols such as HO(CH₂)_(γ)OH,        H₂N(CH₂)_(γ)NH₂, where 1≦γ≦25;    -   (c) strained ring olefins such as dicyclopentadienyl,        norbornenyl, and cyclobutenyl where the chromophore is attached        to any of the saturated carbon linkages in the strained ring        olefins—in this case the monomer may be polymerized via ring        opening metathesis polymerization using an appropriate metal        catalyst as is known in the art; and    -   (d) (—CH₂)_(δ)SiCl₃, (—CH₂)_(δ)Si(OCH₂CH₃)₃, or        (—CH₂)_(δ)Si(OCH₃)₃ where 0≦δ≦25—in this case the monomers can        be reacted with water under conditions known to those skilled in        the art to form either thin film or monolithic organically        modified sol-gel glasses, or modified silicated surfaces.        Alkyl Groups

Unless otherwise indicated explicitly or by context, alkyl group as usedin the above formulae means alkyl groups having up to 25 carbon atomsand includes both branched and straight chain alkyl groups. Exemplaryalkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, in the normal, secondary, iso and neo attachmentisomers.

Aryl Groups

Unless otherwise indicated explicitly or by context, aryl group as usedin the above formulae means aromatic hydrocarbons having up to 20 carbonatoms. Exemplary aryl groups include phenyl, naphthyl, furanyl,thiophenyl, pyrrolyl, selenophenyl, and tellurophenyl.

Fluorenyl- and Dibenzosuberenyl-Containing Chromophores

Chromophores with large two-photon and multiphoton absorptivitiescontaining the fluorenyl moiety will, upon two-photon or multiphotonexcitation, lead to efficient homolytic and/or heterolytic cleavage,releasing the leaving group as a Lewis base, radical species, or ionicspecies and leaving the fluorenyl moiety as a Lewis acid, ionic species,or radical species. Appropriate choice of leaving group will tune theefficiency of cleavage and the ratio of homolytic to heterolyticcleavage. One of ordinary skill in the art will generally know how tochoose the leaving group to vary the cleavage ratio as desired. Examplesof previous literature addressing these issues in the context ofnon-multiphoton absorbing materials includes P. Wan and E. Krogh,“Contrasting Photosolvolytic Reactivities of 9-Fluorenol vs. 5-SuberenolDerivatives. Enhanced Rate of Formation of Cyclically Conjugated Four PiElectrons Carbocations in the Excited State”, J. Am. Chem. Soc., 111,4887-4895 (1989); R. A. McClelland, N, Mathivanan, and S. Steenken,“Laser Flash Photolysis of 9-Fluorenol. Production and Reactivities ofthe 9-Fluorenol Radical Cation and the 9-Fluorenyl Cation”, J. Am. Chem.Soc., 112, 4857-4861 (1990); and R. A. McClelland, F. L. Cozenes, J. Li,and S. Steenken, “Flash Photolysis Study of a Friedel-Crafts Alkylation.Reaction of the Photogenerated 9-Fluorenyl Cation with AromaticCompounds”, J. Chem. Soc., Perkin Trans., 2, 1531-1543 (1996).

Further, we teach that appropriate substitution of the fluorenyl moietyand appropriate choice of environment (i.e., solvent) will tune theefficiency of cleavage and the ratio of homolytic to heterolyticcleavage, as documented in the references above and, by analogy to thebehavior of the diphenylmethyl moiety, in J. Bartl, S. Steenken, M.Mayr, and R. A. McClelland, “Photo-heterolysis and Photo-homolysis ofSubstituted Diphenylmethyl Halides, Acetates, and Phenyl Ethers inAcetonitrile—Characterization of Diphenylmethyl Cations and RadicalsGenerated by 248-nm Laser Flash Photolysis”, J. Am. Chem. Soc., 112,6918-6928 (1990) and M. Lipson, A. A. Deniz, and K. S. Peters, “Natureof the Potential Energy Surfaces for the S_(N)1 Reaction: A PicosecondKinetic Study of Homolysis and Heterolysis for DiphenylmethylChlorides”, J. Am. Chem. Soc., 118, 2992-2997 (1996).

Two-photon and multiphoton absorption by the chromophores describedherein containing the dibenzosuberenyl moiety will lead to efficientcleavage of the leaving group as documented in P. Wan and E. Krogh,“Contrasting Photosolvolytic Reactivities of 9-Fluorenol vs 5-SuberenolDerivatives. Enhanced Rate of Formation of Cyclically Conjugated Four PiElectrons Carbocations in the Excited State”, J. Am. Chem. Soc., 111,4887-4895 (1989); R. A. McClelland, N, Mathivanan, and S. Steenken,“Laser Flash Photolysis of 9-Fluorenol. Production and Reactivities ofthe 9-Fluorenol Radical Cation and the 9-Fluorenyl Cation”, J. Am. Chem.Soc., 112, 4857-4861 (1990); and R. A. McClelland, F. L. Cozenes, J. Li,and S. Steenken, “Flash Photolysis Study of a Friedel-Crafts Alkylation.Reaction of the Photogenerated 9-Fluorenyl Cation with AromaticCompounds”, J. Chem. Soc., Perkin Trans., 2, 1531-1543 (1996).

Synthesis of Fluorenyl and Dibenzosuberenyl Containing Chromophores

Methods for the synthesis of fluorenyl and dibenzosuberenyl containingmolecules are known to practitioners of the art. Exemplary syntheticprocedures are given in the EXAMPLES section below.

Structure of Fluorenyl and Dibenzosuberenyl Containing Chromophores

There are two classes of compounds of the present invention containingthe fluorenyl or dibenzosuberenyl groups: (1) compounds where theendgroups are electron donor groups, and (2) compounds where theendgroups are electron acceptor groups.

(1) Compounds where the Endgroups are Electron Donor Groups

In these formulae:

D_(a) and D_(b)

are the same or different and are N, O, S, or P. To satisfy the properbonding coordination, when D_(a) or D_(b) is an —O— group or —S— group,there is only one R group attached to the D_(a) or D_(b) group; that is,R_(a), R_(b), R_(e), or R_(d) may be nothing, as required.

L_(g)

is a homolytic or heterolytic leaving group and may be

-   -   (i) H;    -   (ii) —OR₁, —NR₁R₂, —N⁺R₁R₂R₃, —PR₁R₂, —P⁺R₁R₂R₃, —SR₁, —S⁺R₁R₂,        Cl, Br, I, —I⁺R₁, where R₁, R₂, and R₃ are defined below    -   (iii) a functional group derived essentially from an amino acids        selected from the group consisting of alanine; valine; leucine;        isoleucine; proline; tryptophan; phenylalanine; methionine;        glycine; serine; threonine; tyrosine; cysteine; glutamine;        asparagine; lysine; arginine; histidine; aspartic acid; and        glutamic acid;    -   (iv) a polypeptide;    -   (v) adenine, guanine, tyrosine, cytosine, uracil, biotin,        ferrocene, ruthenocene, cyanuric chloride and derivatives        thereof; and    -   (vi) methaeryloyl chloride.        Anionic Counterions        an electrically complex neutral. If, for example, the double        positive charge, it will be accompanied by either two anionic        species or by one doubly charged anionic species. may be used        include, but are not limited to, Cl⁻; Br⁻, I⁻, and SbF₆ ⁻.        m, n, o and p

are integers and are independently selected such that 0≦m≦10, 0≦n≦10,0≦o≦0, and 0≦β≦10.

U, V, X, and Y

may be the same or different and may be CR_(k′)═CR_(1′), O, S, orN—R_(m′); R_(k′), R_(1′), and R_(m′) are defined below.

R_(a), R_(b), R_(c), and R_(d)

may be the same or different and may be

-   -   (i) —H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) —(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1),        —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CN, —(CH₂CH₂O)_(α)—(CH₂)_(β)Cl,        —(CH₂CH₂O)_(α)—(CH₂)_(β)Br, —(CH₂CH₂O)_(α)—(CH₂)_(β)I,        —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10, 1≦β≦25, and where        R_(a1), R_(a2), and R_(a3), are the same or different and may be        H or a linear or branched alkyl group with up to 25 carbons;    -   (iv) an aryl group;    -   (v) a fused aromatic ring;    -   (vi) a polymerizable functionality; and    -   (vii) as described above, nothing when D_(a) or D_(b) is an —O—        group or —S— group.        R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(k′), R_(l),        R_(l′), R_(m′), R_(p), R_(q), R_(r), R_(s), R_(t), R_(u), R_(v)        and R₁, R₂, R₃

may be the same or different and may be

-   -   (a) H;    -   (b) a linear or branched alkyl group with up to 25 carbons;    -   (c) —(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1),        —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CN, —(CH₂CH₂O)_(α)—(CH₂)_(β)Cl,        —(CH₂CH₂O)_(α)—(CH₂)_(β)Br, —(CH₂CH₂O)_(α)—(CH₂)_(β)I,        —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10, 1≦β≦25 and        R_(a1), R_(a2) and R_(a3) are the same or different and may be H        or a linear or branched alkyl group with up to 25 carbons;    -   (d) an aryl group,    -   (e) a fused aromatic ring;    -   (f) a polymerizable functionality; or    -   (h) —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, or        phenyl, where R_(e1), R_(e2), R_(e3), R_(e4) are independently        selected from the group consisting of        -   (1) H,        -   (2) a linear or branched alkyl group with up to 25 carbons;        -   (3) phenyl; and        -   (4) a polymerizable functionality.            In a preferred embodiment, R_(q) is the same as R_(t), R_(r)            is the same as R_(v), and R_(s) is the same as R_(u).            Aryl Group

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂ or R₃ is an aryl group, they may bearyl groups of the formula

where E is —S— or —O—, and R_(A1), R_(A2), R_(A3), R_(A4), R_(A5),R_(A6), R_(A7), and R_(A8) are one of the following:

-   -   (i) H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) phenyl; and    -   (iv) —NR_(A9)R_(A10), and —OR_(A11), where R_(A9), R_(A10), and        R_(A11) are independently selected from H, a linear or branched        alkyl group with up to 25 carbons, and phenyl.        Fused Aromatic Ring

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂, or R₃ are fused aromatic rings, theymay be

where * indicates the atom through which the fused aromatic ring isattached.Polymerizable Functionality

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂, R₃, R_(e1), R_(e2), R_(e3), andR_(e4) is a polymerizable functionality, they may be those which can beinitiated by a strong Lewis acid group such as a proton and epoxides(such as cyclohexeneoxide).

Alkyl Groups

Unless otherwise indicated explicitly or by context, alkyl group as usedin the above formulae means alkyl groups having up to 25 carbon atomsand includes both branched and straight chain alkyl groups. Exemplaryalkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, in the normal, secondary, iso and neo attachmentisomers.

Aryl Groups

Unless otherwise indicated explicitly or by context, aryl group as usedin the above formulae means aromatic hydrocarbons having up to 20 carbonatoms. Exemplary aryl groups include phenyl, naphthyl, furanyl,thiophenyl, pyrrolyl, selenophenyl, and tellurophenyl.

(2) Compounds where the Endgroups are Electron Acceptor Groups.

In a preferred embodiment, R_(q) is the same as R_(t), R_(r) is the sameas R_(v), and R_(s) is the same as R_(u).A_(a) and A_(b)

can be the same or different and may be —CHO, —CN, —NO₂, —Br, —Cl, —I orone of the following:

L_(g)

is a homolytic or heterolytic leaving group and may be

-   -   (i) H;    -   (ii) —OR₁, —NR₁R₂, —N⁺R₁R₂R₃, —P⁺R₁R₂, —P⁺R₁R₂R₃, —SR₁, —S⁺R₁R₂,        Cl, Br, I, —I⁺R₁, where R₁, R₂, and R₃ are defined below;    -   (iii) a functional group derived essentially from an amino acids        selected from the group consisting of alanine; valine; leucine;        isoleucine; proline; tryptophan; phenylalanine; methionine;        glycine; serine; threonine; tyrosine; cysteine; glutamine;        asparagine; lysine; arginine; histidine; aspartic acid; and        glutamic acid;    -   (iv) a polypeptide;    -   (v) adenine, guanine, tyrosine, cytosine, uracil, biotin,        ferrocene, ruthenocene, cyanuric chloride and derivatives        thereof; and    -   (vi) methacryloyl chloride.        Anionic Counterions

All cationic species are accompanied by counterions appropriate to makean electrically neutral complex. If, for example, the cationic speciescarries a double positive charge, it will be accompanied by either twosingly charged anionic species or by one doubly charged anionic species.Anionic species that may be used include, but are not limited to, Cl⁻,Br⁻, I⁻, and SbF₆ ⁻.

m, n, and o

are integers and are independently selected such that 0≦m≦10, 0≦n≦10,and 0≦o≦10.

U, V, X, and Y

may be the same or different and may be CR_(k′), —CR_(l′), O, S, orN—R_(m′); R_(k′), R_(l′), and R_(m′) are defined below.

R_(a), R_(b), R_(c), and R_(d)

may be the same or different and may be

-   -   (i) H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) —(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1),        —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CN, —(CH₂CH₂O)_(α)—(CH₂)_(β)Cl,        —(CH₂CH₂O)_(α)—(CH₂)_(β)Br, —(CH₂CH₂O)_(α)—(CH₂)_(β)I,        —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10, 1≦β≦25 and where        R_(a1), R_(a2), and R_(a3), are the same or different and may be        H or a linear or branched alkyl group with up to 25 carbons;    -   (iv) an aryl group;    -   (v) a fused aromatic ring; and    -   (vi) a polymerizable functionality.        R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(k′), R_(l),        R_(l′), R_(m′), R_(p), R_(q), R_(r), R_(s), R_(t), R_(u), R_(v),        and R₁, R₂, R₃

may be the same or different and may be

-   -   (a) H;    -   (b) a linear or branched alkyl group with up to 25 carbons;    -   (c) —(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1),        —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3),        —(CH₂CH₂O)_(α)—(CH₂)_(β)CN, —(CH₂CH₂O)_(α)—(CH₂)_(β)Cl,        —(CH₂CH₂O)_(α)—(CH₂)_(β)Br, —(CH₂CH₂O)_(α)—(CH₂)_(β)I,        —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 1≦α≦10, 1≦β≦25 and where        R_(a1), R_(a2), and R_(a3), are the same or different and may be        H or a linear or branched alkyl group with up to 25 carbons;    -   (d) an aryl group;    -   (e) a fused aromatic ring;    -   (f) a polymerizable functionality; or    -   (g) —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, or        phenyl, where R_(e1), R_(e2), R_(e3), R_(e4) are independently        selected from the group consisting of        -   (1) H;        -   (2) a linear or branched alkyl group with up to 25 carbons;        -   (3) phenyl; and        -   (4) a polymerizable functionality;        -   (5) —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, or            phenyl, Where R_(e1)R_(e2), R_(e3), and R_(e4) may be the            same or different and may be            -   (i) H;            -   (ii) a linear or branched alkyl group with up to 25                carbons;            -   (iii) phenyl; or            -   (iv) a polymerizable functionality.                Aryl Group

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂, or R₃ is an aryl group, they may bearyl groups of the formula

where E is —S— or —O—, and R_(A1), R_(A2), R_(A3), R_(A4), R_(A5),R_(A6), R_(A7), and R_(A8) are one of the following:

-   -   (i) H;    -   (ii) a linear or branched alkyl group with up to 25 carbons;    -   (iii) phenyl; and    -   (iv) —NR_(A9)R_(A10) and —OR_(A8) where R_(A9), R_(A10), and        R_(A11) are independently selected from H, a linear or branched        alkyl group with up to 25 carbons, and phenyl.        Fused Aromatic Ring

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂, or R₃ is a fused aromatic ring, theymay be

where * indicates the atom through which the fused aromatic ring isattached.Polymerizable Functionality

When any of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(k′), R_(l), R_(l′), R_(m′), R_(p), R_(q), R_(r),R_(s), R_(t), R_(u), R_(v), R₁, R₂, R₃, R_(e1), R_(e2), R_(e3), andR_(e4) are polymerizable functionalities, they may be those which can beinitiated by a strong Lewis acid group such as a proton and epoxides(such as cyclohexeneoxide).

Alkyl Groups

Unless otherwise indicated explicitly or by context, alkyl group as usedin the above formulae means alkyl groups having up to 25 carbon atomsand includes both branched and straight chain alkyl groups. Exemplaryalkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, in the normal, secondary, iso and neo attachmentisomers.

Aryl Groups

Unless otherwise indicated explicitly or by context, aryl group as usedin the above formulae means aromatic hydrocarbons having up to 20 carbonatoms. Exemplary aryl groups include phenyl, naphthyl, furanyl,thiophenyl, pyrrolyl, selenophenyl, and tellurophenyl.

EXAMPLES Examples 1-6 Exemplary Syntheses of Compounds V, VI, VIII, IX,X and XI

General Remarks.

¹H and ¹³C spectra were recorded on a GE QE300 spectrometer (1H at 300MHz; ¹³C at 75 MHz). Mass spectral data were acquired by MALDI-TOF.Elemental (CHN) analysis were performed by Analytical Microlabs.

Example 1 Preparation of Compound V

V was synthesized via the Pd(0) catalyzed coupling of2,7-dibromofluorenone with bis-(4n-butylphenyl)-amine under theconditions reported by Barlow and co-workers [Thayumanavan, S., Barlow,S., Marder, S. R., Chem. Mater., 9, 3231-3235 (1997)] and purified bysilica chromatography (10% CH₂Cl₂/hexanes). Blue oil. 43% yield. ¹H NMR(acetone-d6, 300 MHz) δ 7.34 ppm (d, J=8.2 Hz, 2H), δ 7.13 ppm (m, 10H),δ 7.02 ppm (d, J=2.2 Hz, 2H), δ 6.98 ppm (d, J=8.4 Hz, 8H), δ 2.57 ppm(t, J=7.8 Hz, 8H), δ 1.60 ppm (m, 8H), δ 1.35 ppm (m, 8H), δ 0.92 ppm(t, J=7.3 Hz, 12H); ¹³C NMR (CD₂Cl₂, 75 MHz) δ 129.9 ppm (broad), δ125.6 ppm, δ 125.4 ppm, δ125.4 ppm, δ 125.3 ppm, δ 125.2 ppm, δ 118.3ppm, δ 35.5 ppm, δ 34.2 ppm, δ 23.0 ppm, δ 14.2 ppm. MS yields M⁺ withm/z=738. Elemental Analysis Calculated for C₅₃H₅₈N₂O: C, 86.13; H, 7.91;N, 3.79. Found: C, 85.53; H, 7.97; N, 3.76.

Preparation of 2,7-dibromofluorenone

2,7-dibromofluorenone was prepared from fluorenone by the method ofDewhurst and Shah [J. Chem. Soc. C, (Organic) 1737-1740 (1970)] in 66%yield. 2-bromofluorenone is the major impurity and may be removed bywashing the yellow solid with acetone.

Preparation of N,N-bis-(4n-butylphenyl)-amine

The preparation of bis-(4n-butylphenyl)-amine has been reportedpreviously [Thayumanavan, S., Barlow, S., Marder, S. R., Chem. Mater.,9, 3231-3235 (1997)].

Example 2 Preparation of Compound VI

VI was synthesized via the Pd(0) catalyzed Heck coupling ofN,N-bis-(4-n-butylphenyl)-4-styrylamine with 2,7-dibromofluorenone in25% yield. One equivalent of N,Nbis-(4-n-butylphenyl)-4-styrylamine wasadded to 0.45 equivalents 2,7-dibromofluorenone in dry dimethylformamidewith 1.1 equivalents of triethylamine, 5 mole % Pd(OAc)₂, and 25 mole %P(o-tolyl)₃ and heated under argon atmosphere to 100° C. for one week.Reaction was followed by TLC and fresh catalyst and triethylamine wasadded every second day. Quenched reaction with water, washed intomethylene chloride, and removed solvent under reduced pressure. Purifiedby passage through silica (1% EtOAc in hexanes as eluent). Red solid. ¹HNMR (CD₂Cl₂, 300 MHz) δ 7.84 ppm (d, J=1.1 Hz, 2H), δ 7.61 ppm (dd,J=7.9 Hz, 1.5 Hz, 2H), δ 7.54 ppm (d, J=7.8 Hz, 2H), δ 7.42 ppm (d,J=8.8 Hz, 4H), δ7.18 ppm (d, J=16.4 Hz, 2H), δ 7.14 ppm (d, J=8.5 Hz,8H), δ 7.0 ppm (m, 10H), δ 7.02 ppm (m, 10H), δ 2.62 ppm (t, J=7.6 Hz,8H), δ 1.62 ppm (m, 8H), δ 1.40 ppm (m, 8H), δ 0.97 ppm (t, J=7.3 Hz,12H); ¹³C NMR (CD₂Cl₂, 75 MHz) δ 193.9 ppm, δ 148.9 ppm, δ 145.6 ppm, δ143.2 ppm, δ 139.3 ppm, δ 138.7 ppm, δ 135.6 ppm, δ 133.2 ppm, δ 130.5ppm, δ 129.8 ppm, δ 128.0 ppm, δ 125.6 ppm, δ 125.4 ppm, δ 122.4 ppm, δ121.6 ppm, δ 121.0 ppm, δ 35.6 ppm, δ 34.3 ppm, δ 23.0 ppm, δ 14.3 ppm.MS yields M⁺ with m/z=942.8 Elemental Analysis Calculated for C₆₉H₇₀N₂O:C, 87.86; H, 7.48; N, 2.97. Found: C, 87.58; H, 7.41; N, 2.99.

Preparation of N,N-bis-(4-n-butylphenyl)-4-styrylamine

4-(N,N-Bis-(4-n-butylphenyl)amino)benzaldehyde [Thayumanavan, S.,Barlow, S., Marder, S. R., Chem. Mater., 9, 3231-3235 (1997)] wasstirred with 1.5 equivalents methyl triphenylphosphoniumbromide and 1.5equivalents sodium t-butoxide in dry tetrahydrofuran under argonatmosphere overnight at RT before aqueous work-up to make theN,N-bis-(4-n-butylphenyl)-4-styrylamine. The product was purified bypassage through a silica plug with hexanes and collected in 69% yield.¹H NMR (acetone-d6, 300 MHz) δ 7.30 ppm (d, J=8.6 Hz, 2H), δ 7.12 ppm(d, J=8.4 Hz, 4H), δ 6.96 ppm (d, J=8.4 Hz, 4H), δ 6.92 ppm (d, J=8.6Hz, 2H), δ 6.65 ppm (dd, J=16.4 Hz, 10.9 Hz, 1H), δ 5.65 ppm (dd, J=17.6Hz, 1.0 Hz, 1H), δ 5.10 ppm (dd, J=10.9 Hz, 0.9 Hz, 1H), δ 2.58 ppm (t,J=7.5 Hz, 4H), δ 1.58 ppm (m, 4H), δ 1.36 ppm (m, 4H), δ 0.93 ppm (t,J=7.3 Hz, 6H).

Example 3 Preparation of Compound VIII

V was reduced quantitatively to VIII with sodium borohydride inTHF/ethanol at room temperature under air at RT. The course of thereaction was easily followed by the disappearance of the deep blue colorof V. Light brown solid. ¹H NMR (acetone-d6, 300 MHz) δ 7.52 ppm (d,J=8.2 Hz, 2H), δ 7.24 ppm (d, J=1.6 Hz, 2H), δ 7.14 ppm (d, J=8.6 Hz,8H), δ 7.0 ppm (m, 10H), δ 5.43 ppm (d, J=6.7 Hz, 1H), δ 4.75 ppm (d,J=7.3 Hz, 1H), δ 2.60 ppm (t, J=7.6 Hz, 8H), δ 1.60 ppm (m, 8H), δ 1.39ppm (m, 8H), δ 0.94 ppm (t, J=7.3 Hz, 12H).

Example 4 Preparation of Compound IX

IX was synthesized via a Williamson Ether synthesis from VIII. 1.2equivalents of NaH were added to a deoxygenated solution of 1 equivalentof VIII and 2 equivalents of methyliodide in dry THF. Following aqueouswork-up, IX was purified by silica column chromatography (0.5% EtOAc inhexanes as eluent). Brown oil, 60% yield. ¹H NMR (acetone-d6, 300 MHz) δ7.56 ppm (d, J=8.2 Hz, 2H), δ 7.16 ppm (m, 10H), δ 7.02 ppm (m, 10H), δ5.39 ppm (s, 1H), δ 3.03 ppm (s, 3H), δ 2.60 ppm (t, J=7.6 Hz, 8H), δ1.60 ppm (m, 8H), δ 1.38 ppm (m, 8H), δ 0.94 ppm (t, J=7.3 Hz, 12H).

Example 5 Preparation of Compound X

VIII was converted quantitatively to X by room temperature reaction withexcess acetyl chloride in pyridine with N,N-dimethylpyridine. Solventwas removed under reduced pressure, product was taken up into hexanes,washed with water, and solvent was removed under reduced pressure. ¹HNMR (acetone-d6, 300 MHz) δ 7.51 ppm (d, J=8.2 Hz, 2H), δ 7.20 ppm (d,J=1.9 Hz, 2H), δ 7.12 ppm (d, J=8.4 Hz, 8H), δ 6.98 ppm (m, 10H), δ 6.57ppm (s, 1H), δ 2.58 ppm (t, J=7.7 Hz, 8H), δ 1.98 ppm (s, 3H), 1.60 ppm(m, 8H), δ 1.39 ppm (m, 8H), δ 0.93 ppm (t, J=7.3 Hz, 12H).

Example 6 Preparation of Compound XI

XI was reduced quantitatively to VI with sodium borohydride inTHF/ethanol at room temperature under air at RT. The course of thereaction was easily followed by the disappearance of the red color ofVI. XI may be recrystallized from hexanes. Yellow crystals. ¹H NMR(CD₂Cl₂, 300 MHz) δ 7.84 ppm (s, 2H), δ 7.65 ppm (d, J=7.9 Hz, 2H), δ7.54 ppm (d, J=7.9 Hz, 2H), δ 7.42 ppm (d, J=8.7 Hz, 4H), δ 7.08 ppm (m,12H), δ 5.65 ppm (d, J=9.5 Hz, 1H), δ 2.62 ppm (t, J=7.6 Hz, 8H), δ 2.10ppm (d, J=9.6 Hz, 1H), δ 1.61 ppm (m, 8H), δ 1.40 ppm (m, 8H), δ 0.98ppm (t, J=7.3 Hz, 12H).

Example 7 Two-Photon Polymerization Using bis-dibutylaminostilbene(BDAS) as a Two-Photon Initiator

A two-photon “polymerization action spectrum” was investigated forbis-dibutylaminostilbene (BDAS). This spectrum shows that the rate ofpolymerization for monomethyl-ether hydroquinone (MEHQ)-inhibitedSartomer SR9008 initiated by BDAS roughly follows the two-photonabsorptivity dispersion curve, but peaks at a slightly lower wavelength.

To obtain the “action spectrum” for BDAS polymerization in SR9008, a 2.5mM solution was used. The monomer included MEHQ inhibitor as supplied bySartomer since the rate of initiation by BDAS is quite high. The samplewas irradiated from 540 nm to 635 nm in steps of 5 nm. The sample wasexposed in a square array of time along one axis and wavelength alongthe other. Volumes of the resulting polymer columns were measured by SEMand the rate of polymerization taken as the slope of polymer volumeversus time.

A dose array experiment was performed for BDAS (#1) in MEHQ-inhibitedSR9008 triacrylate monomer to investigate the wavelength dependence ofthe polymerization rate, R_(p). FIG. 1 shows a plot of R_(p) as afunction of initiation wavelength. Also on this plot is the two-photonabsorptivity, δ, obtained by ps (picosecond) non-linear fluorescencemeasurements of a 1 mM solution of BDAS in toluene. Values of R_(p) weredetermined using a 2.5 mM BDAS solution in SR9008. R_(p) is greatest atabout 590 nm, 15 nm below the maximum value of δ at 605 nm. Thediscrepancy in wavelength may be due to linear absorption by the BDASradical centered at 600 nm. Polymerization stopped entirely at 645 nmeven though there was some two-photon absorption out to about 680 nm.

Example 8 Two-Photon Initiated Polymerization and 3D Microfabrication ofPolymeric Microstructures

Microfabrication was performed in solid films consisting of 30% w/wpolymer binder (PSAN) (75% polystyrene:25% polyacrylonitrile copolymer),69.9% w/w reactive monomer, and 0.1% w/w dye1,4-bis(bis(dibutylamino)styryl) 2,5-dimethoxybenzene (compound #41).The monomer portion was 50% inhibitor-free Sartomer SR9008 (chosen forits good adhesion properties) and 50% Sartomer SR368 (an isocyanuratetriacrylate, chosen for its good mechanical stability). Solutions ofthis composition were prepared in dioxane such that the PSANconcentration was 200 mg/ml to obtain the proper viscosity. A castingblade was used to prepare films from solution, with a wet thicknesssetting of 500-700 μm. Once the films dried, the thickness was about120-180 μm. Exposure was performed using a two-photon microscopeincorporating a Ti:Sapphire laser operating at 75 MHz with a pulsewidthof about 150 fs. The wavelength used was 730 nm, the two-photonabsorption maximum of #41(1,4-bis(bis(dibutyl-amino)styryl-2,5-dimethoxybenzene, and the lightwas focused through an oil-immersion objective with NA=1.4. X-Y-Zcontrol of the sample was accomplished using a manipulator mounted onthe microscope stage. After exposure, the unpolymerized film was washedaway with dimethylformamide (DMF) and the features were characterizedusing SEM.

It was found that the linewidths polymerized at 730 nm (approx. 1.5 μm)were about 25% smaller than at 800 nm given the same intensity and scanrate. FIG. 2 shows cantilever and tapered waveguide structuresfabricated using the procedures described above. Cantilevers withextended lengths of up to 50 μm were fabricated with no apparent sag ofthe unsupported arm. These cantilevers may be useful in the fabricationof optically-based chemical sensors. The waveguide structure wasproduced with a linespacing of 2 μm.

Example 9 Two-Photon Photodeposition of Silver Metal

In addition to using the two-photon process to initiate polymerization,it is also possible to perform metallization using this technique.Swainson provided a method for depositing Ag or CuO_(x) using methyleneblue as a sensitizer for one-photon photoreduction of a metal cation toits elemental form [W. K. Swainson and S. D. Kramer, “Method and Mediafor Accessing Data in Three Dimensions,” U.S. Pat. No. 4,471,470(1984)]. This process is modified for simultaneous two-photonphotoreduction by use of chromophores described in this disclosure. Theability to deposit metal by a two-photon process allows fabrication ofcomplex three-dimensional metallic or polymer/metal compositestructures.

A solution of 1 g AgNO₃ dissolved in 10 ml DI H₂O was titrated withNH₄OH until the initially formed, dark precipitate was dissolved. Twodrops of triethanolamine (TEA) was added to this solution along withenough chromophore, either methylene blue (MB) or lysine-substitutedBDAS (LBDAS), to form a 10⁻³ M solution of the dye. This solution wasused as prepared for solution studies or was added to an 8% by weightsolution of poly(vinyl alcohol) (PVA) in DI H₂O to form a castable,solid film.

Initial studies of Ag photodeposition were done using single-photonexcitation in methylene blue solutions. Excitation was done at 600 nmusing a 20 Hz Nd:YAG-pumped dye laser. Silver deposition was observed onthe glass walls of the cell containing the silver nitrate solution.Also, a plume of silver particles could be seen in the solution,emanating from the focal point of the laser. Scanning electronmicroscopy (SEM) was used to examine the morphology of the depositedsilver and showed that the deposited film consists of many smallagglomerates. X-ray analysis confirmed that these small particles wereindeed silver. Because of the roughness of these films, they are notuseful for producing mirrored surfaces. The confined surface (againstthe glass wall of the cell), however, was a highly reflective mirror.The deposited lines were not conducting.

This technique for silver deposition from aqueous solutions was alsoattempted using LBDAS. This solution was pumped by two-photon excitationat 600 nm. Small amounts of Ag were deposited onto the walls of the celland some Ag particulates were formed in solution and then settled to thebottom of the cuvette.

Initial attempts to fabricate solid or gel photopolymer films for Agdeposition were based on the aqueous silver nitrate chemistry and thusrequired a water soluble polymer. PVA was chosen but, because it issoluble only in boiling water, the silver salt cannot be prepareddirectly with the polymer solution or the reduction to Ag will occurthermally. Instead, the polymer solution was prepared and cooled andthen mixed with the AgNO₃ solution. The combined solution was thenpoured into small polystyrene petri dishes and left under a halogenlamp. The photoreduction of the silver salt occurred as water evaporatedfrom the film. The first film prepared by this method contained 17% Agby weight. The film had good mechanical properties and was easily peeledaway from the petri dish. It was dark-colored and transmitted only redlight, apparently because of the size of the Ag particles in the film.The resistance of this film was 5.5 MΩ. A second film was prepared witha 52% loading of Ag. This film had a shiny, metallic appearance but thefilm was still strong and flexible. The resistance of this film droppedto 80 kΩ.

The next step was to search for a system that allows two-photondeposition of Ag. Qualitative two-photon fluorescence measurementsindicated that because methylene blue had no significant two-photonabsorption in the spectral region of interest, a different chromophorewas needed. BDAS was chosen first and was incorporated into an aqueoussolution of cellulose acetate hydroxyethyl ether and silvertetrafluoroborate (AgBF₄) by dissolving it in dioxane, which iscompletely miscible with water. In this case, AgBF₄ was soluble in waterwithout the addition of NH₄OH and no TEA was necessary. Upon introducingthe first drop of the BDAS solution into the silver salt solution, Agprecipitated out. Table 1 shows electrochemical data for the reductionof Ag⁺ in different solvents and free energies for electron transferfrom different two-photon chromophores to Ag⁺. It is clear that in anysolvent, BDAS is such a strong reducing agent that Ag⁺ will always bereduced thermally. The ideal situation is to use a chromophore that willnot thermally reduce Ag⁺, but will upon exposure to light. Since theHOMO-LUMO (highest occupied molecular orbital-lowest unoccupiedmolecular orbital) gap of BDAS and 4,4′-bis(m-tolylphenylamino)biphenyl(TPD) molecules is on the order of 3000 meV, any of these molecules willphotoreduce Ag⁺ in any solvent upon excitation.

TABLE 1 Electrochemical data for the reduction of Ag⁺ in varioussolvents. ΔG (meV) Solvent E_(red.) Ag⁺/Ag (mV)^((a)) BDAS TPD p-CNTPD^((b)) MeCl₂ 650 −685 −270 −75 DMF 490 −525 −110 85 H₂O 480 −515 −10095 Pyridine 430 −465 −50 145 THF 410 −445 −30 165 Acetone 180 −215 200395 CH₃CN 40 −75 340 535 ^((a))Values of E_(red) are given vs. FcH⁺/FcH^((b))p-CN TPD = 4,4′-bis(p-cyanophenyl-m-tolylamino)biphenyl

TPD was tried in an aqueous solution of AgBF₄ since electron transfer isonly slightly downhill in this system. Although some of the TPDprecipitated out of solution, it was possible to cast a film of thismaterial. A portion of the solution that was not used was placed insunlight and, within minutes, Ag had formed in the solution. The filmwas kept in the dark for several days to allow the water to evaporate.After this time, the solution was mostly clear, containing white TPDprecipitates and some regions where it appears that Ag began to form.The clear portion of the film was exposed to 532 nm ns laser pulses andfairly thick deposits of Ag quickly formed in the exposed regions. Linesand patterns of Ag were deposited in this manner.

Because of the limited solubility of TPD compounds in aqueous solutionsand the slow evaporation rate of water when casting films, a systembased upon a non-aqueous solvent is desirable. Bis(phenyl,4-cyanophenylamino) biphenyl (#97) was selected as the two-photonchromophore because it has one of the highest oxidation potentials ofany of the two-photon chromophores that have been studied in this group(575 mV vs. FcH⁺/FcH). Solutions of #97 and AgBF₄ were prepared inmethylene chloride, THF, acetone, toluene, and acetonitrile and theformation of Ag was observed in all solvents except acetonitrile. Thisresult was somewhat surprising since the value of ΔG is positive for THF(165 meV) and acetone (395 meV). The value of ΔG in acetonitrile isquite high at 535 meV. Unfortunately, it is difficult to find a polymerthat is soluble in acetonitrile—at this time cellulose acetate is theonly polymer found. Photopolymer films made with #97 and AgBF₄ incellulose acetate/acetonitrile solutions will be studied in the nearfuture.

Example 10 Two-Photon Excitable Photoacid Generators

The use of free-radical polymerization based on electron transfer fromtwo-photon chromophores to acrylate monomers has proven very successfulfor the fabrication of microscale three-dimensional objects. Periodicstructures suggestive of photonic crystals, tapered waveguide couplers,and cantilever-shaped objects have been reported in previous months.Also, high-density optical data storage based on acrylate polymerizationhas been demonstrated. While the size of the bits written by this methodis sufficiently small to obtain storage densities of 1 terabit/cm³, thespeed of the recording process is too slow. Parallelization of therecording process can decrease the overall processing time, but it isalso highly desirable to make the inherent response of the photopolymermaterial faster.

Researchers at IBM have developed chemistry for photoresist technologybased on processes involving photoacid generators (PAG)—materials thatproduce acidic species upon exposure to light [H. Ito, “ChemicalAmplification Resists: History and Development Within IBM,” IBM Journalof Research & Development, 41, 69 (1997); R. D. Allen, G. M. Wallraff,D. C. Hofer, and R. R. Kunz, “Photoresists for 193-nm Lithography,” IBMJournal of Research & Development, 41, 95 (1997); J. M. Shaw, J. D.Gelorme, N. C. LaBianca, W. E. Conley, and S. J. Holmes, “NegativePhotoresists for Optical Lithography,” IBM Journal of Research &Development, 41, 81 (1997)]. The driving force of this research is todevelop photoresists that can be used at 193 nm, a wavelength necessaryto increase the density of components in integrated circuits. Thephotoacid generator can initiate different chemical processes dependingon the composition of the photopolymer material. For instance, thephotoacid can be used to initiate cross-linking of epoxide groups. K. Y.Lee, N. LaBianca, S. A. Rishton, S. Zolghamain, J. D. Gelorme, J. Shaw,and T. H.-P. Chang, “Micromachining Applications of a High ResolutionUltrathick Photoresist,” J. Vac. Sci. Technol. B, 13, 3012 (1995); H.Lorenz, M. Despont, N. Fahrni, N. LaBianca, P. Renaud, and P. Vettiger,“SU-8: A Low-cost Negative Resist for MEMS,” J. Micromech. Microeng.,121 (1997)] or it can convert aqueous-insoluble ester groups intoaqueous-soluble acid groups [R. D. Allen, G. M. Wallraff, W. D.Hinsberg, and L. L. Simpson, “High Performance Acrylic Polymers forChemically Amplified Photoresist Applications,” J. Vac. Sci. Technol. b,9, 3357 (1991)]. The advantage to the second process is that it can bemade to be catalytic, that is, for each functional group converted, aproton is formed which can then go on to convert another group.

In this example, we extend PAG chemistry discussed above to the realm oftwo-photon excitation. All of the advantages of the two-photon processthat have been demonstrated in acrylate polymerization can be realized.At the same time, PAG chemistry may provide a better materials systemfor data storage or microfabrication than acrylates. Increasedsensitivity due to catalytic processes, increased mechanical stability,and decreased shrinkage upon polymerization are all possibleimprovements to be made. In order to realize these benefits, PAGchromophores with large two-photon absorption coefficients must bedeveloped.

To this end, sulfonium salts with a two-photon absorbing counterion orthat have significant two-photon absorption themselves are beingconsidered. First of these is triphenylsulfoniumdimethoxyanthracenesulfonate (TPS-DMAS). This material is notcommercially available but has been made by anion exchange betweenTPS-HFA and sodium dimethoxyanthracenesulfonate (Na-DMAS) [K. Naitoh, T.Yamaoka, and A. Umehara, “Intra-ino-pair Electron Transfer Mechanism forPhotolysis of Diphenyliodonium Salt Sensitized by9,10-Dimethoxyanthracene-2-sulfonate Counteranion,” Chem. Lett., 1869(1991)]. 150 mg of sodium dimethoxyanthracene sulfonate (Na-DMAS) wasdissolved in 50 ml of hot DI H₂O. To this hot solution was added 440 μLof a 50 wt % solution of triphenylsulfonium hexafluoroantimonate(TPS-SbF₆ (also referred to herein as TPS-HFA)), giving equimolaramounts of the two salts. The solution was vigorously shaken and thencooled at 4° C. for about 16 hours. A waxy solid precipitated onto thewalls of the flask during this time. The solid was dried overnight undervacuum. At this point, a viscous liquid was present at the bottom of theflask, presumably propylene carbonate. The precipitate was dissolvedinto about 4 ml acetonitrile (CH₃CN) and re-precipitated from 350 ml DIH₂O at 4° C. This solution was vacuum filtered through a fine frit,scraped and dried overnight under vacuum at 35-40° C. The yield for theentire procedure was about 75%. Solutions of all three salts wereprepared in acetonitrile and their UV-Vis spectra are shown in FIG. 3 aalong with their structures (FIG. 3 b). It is clear that the spectrum ofTPS-DMAS prepared by this method has features of both Na-DMAS andTPS-HFA, as desired. Solubility properties also suggest that the saltobtained by this preparation is TPS-DMAS.

A 5×10⁻⁴ M solution of TPS-DMAS was prepared in CH₃CN. The two-photonfluorescence signal was measured using an unamplified PMT at 700 V underexcitation at 2 mJ by a ns OPO tunable laser. The fluorescence signalwas collected through a 450 nm shortpass filter and a monochromatortuned to 430 nm, the fluorescence maximum of TPS-DMAS. Two-photonfluorescence excitation spectra were measured for both TPS-DMAS andNa-DMAS by scanning the OPO from 500 nm to 690 nm. Some backgroundsignal was detected from CH₃CN alone and was subtracted from the samplesignals at each wavelength.

FIG. 4 shows the two-photon fluorescence excitation spectra for bothTPS-DMAS and Na-DMAS. Both compounds show identical features, althoughNa-DMAS appeared more fluorescent than TPS-DMAS. Both show a broadfeature centered at about 570 nm. Also, there is a sharp feature at 645nm which is apparently an artifact due to 400 nm light “leaking” out ofthe laser when excitation around 640 nm was employed.

FIG. 5 shows that the fluorescence signal when pumped at 560 nm, thetwo-photon absorption maximum, of both compounds is proportional to thesquare of the excitation energy, consistent with a two-photon process.This observation also indicates that there are no saturation effects atthis pump energy. We have also observed two-photon excited fluorescenceof TPS-DMAS following excitation with 150 fs laser pulses at 800 nm.

These observations show that there is sufficient two-photon absorptionin TPS-DMAS at 560 nm to make it a good candidate for use as atwo-photon photoacid generator at this wavelength. The utility of thismaterial in combination with multi-functional epoxide resins or as amaterial for selectively imparting water solubility to acrylate polymersremains to be explored.

FIG. 6 shows potential structures of PAGs that inherently possess goodtwo-photon absorption. These molecules actually contain two PAG groupswhich could provide true chemical amplification by producing two protonsfrom a single functional group modification. Strong two-photonabsorption is anticipated because the A-Π-A and A-D-A structures areanalogous to D-Π-D and D-A-D molecules already shown to have hightwo-photon absorption cross-sections. The alkyl chains on the proposedstructures are present to improve the solubility of the chromophores.

Example 11 Two-Photon Polymerization of an Aniline-SubstitutedDiacrylate Monomer (ADA) and Subsequent Deposition of Silver Onto thisPolymer

ADA is a difunctional monomer. The structure of ADA is given in FIG. 7.A neat solution of aniline diacrylate (ADA) was placed in a dose arraycell and polymerized using a collimated beam of ns pulses at 600 nm.Unexposed monomer was then washed away using THF. The columns were thensoaked in a concentrated solution of AgBF₄ in CH₃CN for 3 hours andanalyzed using scanning electron microscopy (SEM) and energy-dispersiveX-ray fluorescence spectroscopy (EDS).

A photopolymer film of ADA was prepared by dissolving 600 mgpolystyrene-co-acrylonitrile (PSAN), 470 mg Sartomer SR368, 425 μLSartomer SR9008, and 470 μL ADA in 3 ml of dioxane. This solution wascast onto a glass microscope slide using a casting knife set for a wetfilm thickness of 1 mm. Lines were polymerized using collimated light at600 nm from a ns OPO laser. After polymerization, the unexposed materialwas removed using dimethylformamide (DMF) and the substrate was soakedfor 3 hours in a concentrated solution of AgBF₄ in CH₃CN.

The aniline group in ADA is a sufficiently strong electron donor tothermally reduce Ag⁺ to metallic Ag. Initial attempts to polymerize thismonomer were done in a dose array fashion. It was found thatpolymerization occurred in neat monomer at 600 nm without the additionof any other two-photon chromophore. The absorption spectrum of ADA isgiven in FIG. 8 and it is clear that there is no linear absorption at600 nm. However, the aniline absorption at 300 nm is two-photon allowedsince the molecule does not have a center of symmetry. This demonstratesthat the polymerization at 600 nm is due to two-photon absorption.

Upon two-photon excitation at 600 nm, the polymerization appears toproceed by intramolecular charge transfer from the aniline group to thereactive acrylate centers. If this is the case, the fluorescence of ADAshould be quenched relative to that of aniline alone. FIG. 9 shows thatthis is indeed the case.

After polymerization of columns from ADA, the polymer was soaked inAgBF₄ to test the ability of the ADA polymer, poly(ADA), to reduce themetal cations. Indeed, the columns darkened upon exposure. SEMmicrographs (FIG. 10) show that the coated polymer's morphology isconsistent with previous observations in polymer columns produced bytwo-photon dose array experiments. X-ray fluorescence spectra (FIG. 11)indicate that the coating contains Ag and BF₄-anions. Quantitativeanalysis was not available by this technique.

Polymerization has also been performed in photopolymer films containingADA. In this case, three lines were written at different energy levelsand then the unexposed film was washed away. The lines remained,attached to the glass substrate. The lines darkened upon exposure toAgBF₄ solution, but no analysis of the coating has been performed yet.

We claim:
 1. A compound selected from the group consisting of

where Aa and Ab are independently selected from the group consisting ofS⁺and I⁺; m, n, o are independently selected from the range of integersgreater than or equal to zero and less than or equal to ten, wherein mand/or o are at least 1; X, Y, Z are independently selected from thegroup consisting of CR_(k)═CR_(l), O, S, and N—R_(m), where R_(k),R_(l), and R_(m) are defined below; R_(a), R_(b), R_(c), R_(d) areindependently selected from the group consisting of (i) H; (ii) a linearor branched alkyl group with up to 25 carbons; (iii)(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10 and 1≦β≦25; (iv) an arylgroup; (v) a fused aromatic ring; (vi) a polymerizable functionality;and (vii) wherein one of R_(a) and R_(b) is not present when A_(a) isI⁺, and one of R_(c) and R_(d) is not present when A_(b) is I⁺; andR_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l) and R_(m) areindependently selected from the group consisting of (a) H; (b) a linearor branched alkyl group with up to 25 carbons; (c)—(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1), —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),—(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3), —(CH₂CH₂O)_(α)(CH₂)_(β)CN,—(CH₂CH₂O)_(α)—(CH₂)_(β)Cl, —(CH₂CH₂O)_(α)—(CH₂)_(β)Br,—(CH₂CH₂O)_(α)—(CH₂)_(β)I, —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10and 1≦β≦25; (d) an aryl group; (e) a fused aromatic ring; (f) apolymerizable functionality; and (g) a group selected from the groupconsisting of —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, andphenyl, where R_(e1), R_(e2), R_(e3), R_(e4) are independently selectedfrom the group consisting of (1) H; (2) a linear or branched alkyl groupwith up to 25 carbons; (3) phenyl; and (4) a polymerizablefunctionality.
 2. A compound according to claim 1, further comprising ananion selected from the group consisting of Cl⁻, Br⁻, I⁻, and SbF₆ ⁻. 3.A compound according to claim 1, wherein the R_(a), R_(b), R_(c), R_(d),R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l), R_(m), R_(e1),R_(e2), R_(e3), or R_(e4) polymerizable functionalities are selectedfrom the group consisting of vinyl, allyl, 4-styryl, acroyl, methacroyl,epoxides, acrylonitrile, isocyanate, isothiocyanate, strained ringolefins, (—CH₂)_(δ)SiCl₃, (—CH₂)_(δ)Si(OCH₂CH₃)₃, and(—CH₂)_(δ)Si(OCH₃)₃ where 0<δ<25.
 4. A compound according to claim 3,wherein the polymerizable functionality strained ring olefins areselected from the group consisting of dicyclopentadienyl, norbornenyl,and cyclobutenyl.
 5. A compound according to claim 1, wherein the R_(a),R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k),R_(l), R_(m), R_(e1), R_(e2), R_(e3), or R_(e4) linear or branched alkylgroups are selected from the group consisting of methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, nonyl, in the normal, secondary,iso and neo attachment isomers.
 6. A compound according to claim 1,wherein the R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l), or R_(m) aryl group is selected from thegroup consisting of

where E is selected from the group consisting of —S— and —O—, andR_(A1), R_(A2), R_(A3), R_(A4), R_(A5), R_(A6), R_(A7), and R_(A8) areselected from the group consisting of (i) H; (ii) a linear or branchedalkyl group with up to 25 carbons; (iii) phenyl; and (iv)—NR_(A9)R_(A10), and —OR_(A11), where R_(A9), R_(A10), and R_(A11) areindependently selected from the group consisting of —H, a linear orbranched alkyl group with up to 25 carbons, and phenyl.
 7. A compoundaccording to claim 6, wherein the aryl groups are selected from thegroup consisting of phenyl, naphthyl, furanyl, thiophenyl, pyrrolyl,selenophenyl and tellurophenyl.
 8. A compound according to claim 1,wherein the R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l), or R_(m) fused aromatic ring is selectedfrom the group consisting of

where * indicates the atom through which the fused aromatic ring isattached.
 9. A photoactivated compound, wherein the compound isactivated via multiphoton absorption, said compound selected from thegroup consisting of

where Aa and Ab are independently selected from the group consisting ofS⁺and I⁺; m, n, o are independently selected from the range of integersgreater than or equal to zero and less than or equal to ten, wherein mand/or o are at least 1; X, Y, Z are independently selected from thegroup consisting of CR_(k)═CR_(l), O, S, and N—R_(m), where R_(k),R_(l), and R_(m) are defined below; R_(a), R_(b), R_(c), R_(d) areindependently selected from the group consisting of (i) H; (ii) a linearor branched alkyl group with up to 25 carbons; (iii)(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10 and 1≦β≦25; (iv) an arylgroup; (v) a fused aromatic ring; (vi) a polymerizable functionality;and (vii) wherein one of R_(a) and R_(b) is not present when A_(a) isI⁺, and one of R_(c) and R_(d) is not present when A_(b) is I⁺; andR_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l) and R_(m) areindependently selected from the group consisting of (a) H; (b) a linearor branched alkyl group with up to 25 carbons; (c)—(CH₂CH₂O)_(α)—(CH₂)_(β)OR_(a1), —(CH₂CH₂O)_(α)—(CH₂)_(β)NR_(a2)R_(a3),—(CH₂CH₂O)_(α)—(CH₂)_(β)CONR_(a2)R_(a3), —(CH₂CH₂O)_(α)(CH₂)_(β)CN,—(CH₂CH₂O)_(α)—(CH₂)_(β)Cl, —(CH₂CH₂O)_(α)—(CH₂)_(β)Br,—(CH₂CH₂O)_(α)—(CH₂)_(β)I, —(CH₂CH₂O)_(α)—(CH₂)_(β)-Phenyl, where 0≦α≦10and 1≦β≦25; (d) an aryl group; (e) a fused aromatic ring; (f) apolymerizable functionality; and (g) a group selected from the groupconsisting of —NR_(e1)R_(e2), —OR_(e3), —SR_(e4), —F, —Br, —Cl, —I, andphenyl, where R_(e1), R_(e2), R_(e3), R_(e4) are independently selectedfrom the group consisting of (1) H; (2) a linear or branched alkyl groupwith up to 25 carbons; (3) phenyl; and (4) a polymerizablefunctionality.
 10. A compound according to claim 9, further comprisingan anion selected from the group consisting of Cl⁻, Br⁻, I⁻, and SbF₆ ⁻.11. A compound according to claim 9, wherein the R_(a), R_(b), R_(c),R_(d), R_(e), R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l), R_(m),R_(e1), R_(e2), R_(e3), or R_(e4) polymerizable functionalities areselected from the group consisting of vinyl, allyl, 4-styryl, acroyl,methacroyl, epoxides, acrylonitrile, isocyanate, isothiocyanate,strained ring olefins, (—CH₂)_(δ)SiCl₃, (—CH₂)_(δ)Si(OCH₂CH₃)₃, and(—CH₂)_(δ)Si(OCH₃)₃ where 0<δ<25.
 12. A compound according to claim 11,wherein the polymerizable functionality strained ring olefins areselected from the group consisting of dicyclopentadienyl, norbornenyl,and cyclobutenyl.
 13. A compound according to claim 9, wherein theR_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h), R_(i), R_(j),R_(k), R_(l), R_(m), R_(e1), R_(e2), R_(e3), or R_(e4) linear orbranched alkyl groups are selected from the group consisting of methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, in thenormal, secondary, iso and neo attachment isomers.
 14. A compoundaccording to claim 9, wherein the R_(a), R_(b), R_(c), R_(d), R_(e),R_(f), R_(g), R_(h), R_(i), R_(j), R_(k), R_(l), or R_(m) aryl group isselected from the group consisting of

where E is selected from the group consisting of —S— and —O—, andR_(A1), R_(A2), R_(A3), R_(A4), R_(A5), R_(A6), R_(A7), and R_(A8) areselected from the group consisting of (i) H; (ii) a linear or branchedalkyl group with up to 25 carbons; (iii) phenyl; and (iv)—NR_(A9)R_(A10), and —OR_(A11), where R_(A9), R_(A10), and R_(A11) areindependently selected from the group consisting of —H, a linear orbranched alkyl group with up to 25 carbons, and phenyl.
 15. A compoundaccording to claim 14, wherein the aryl groups are selected from thegroup consisting of phenyl, naphthyl, furanyl, thiophenyl, pyrrolyl,selenophenyl and tellurophenyl.
 16. A compound according to claim 9,wherein the R_(a), R_(b), R_(c), R_(d), R_(e), R_(f), R_(g), R_(h),R_(i), R_(j), R_(k), R_(l), or R_(m) fused aromatic ring is selectedfrom the group consisting of

where * indicates the atom through which the fused aromatic ring isattached.
 17. The compound of claim 9, wherein the compound has theformula


18. The compound of claim 9, wherein the compound has the formula


19. The compound of claim 9, wherein the compound has the formula


20. The compound of claim 9, wherein the compound has the formula